Method and apparatus for obtaining stereoscopic effects



May 14, 1935. E. P. LE BARBIER 2,001,256

METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original FiledMay 1, 1931 3 Sheets-Sheet l May 14, 1935. E. P. L. LE BARBIER METHODAND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original Filed May 1,1951 3 Sheets-Sheet 2 May 14, 1935. p, LE BARBER 2,001,256

METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original FiledMay 1. 1931 3 Sheets-Sheet 3 fmi/e firm: 140/3 e g f/e 7 mm M.

UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR OBTAININGSTEREOSCOPIC EFFECTS Emile Pierre Louls Le BarblerQNioe, FranceApplication May 1, 1931, Serial N0. 534,179. Be-

newed February 26, 1935.

3 Claims.

The present invention relates to methods in apparatus for obtainingstereoscopic effects in a single positive or negative.

It is well known that stereoscopic elfects may 5 be obtained bysimultaneously photographing a single object from two different anglesoptically combining the two images thus produced. It is not so commonlyknown that the human iris normally varies very rapidly in diameter andgives the sensation of depth due to these variations. As tending toprove the latter, it is to be noted, that when atropine or any similardrug capable of paralyzing the iris is injected into the human eye,variations in diameter of the pupil are done away with and thepossibility of judging depth is simultaneously lost.

One of the objects of the present invention is to produce photographsand, more particularly, cinematography positives and negatives whicheach, taken alone, give the sensation of depth without combining asecond image therewith in any way, relief being obtained by varying theeffective aperture of the objective during exposure (or projection).

Other objects will appear in the course of the detailed description nowto be given with reference to the accompanying drawings, in which:

Figs. 1 to 7 are seven diagrams illustrating the principle upon whichthe invention is based;

Fig. 8 shows one constructive embodiment of the invention;

Fig. 9 illustrates a second form of the invention;

Figs. 10 to 12 inclusive show various forms of the invention adapted toproduce effects of the type illustrated in Figs. 1 to 7.

The human iris has a double function (1) to limit the amount of lightentering the eye and (2) to produce a sensation of relief, this lattereffect being produced by rapid variation of its diameter within certainlimits. In the structures forming the subject matter of the presentinvention these functions are divided between two diaphragms, oneserving, as in ordinary cameras, to limit the amount of light traversingthe objective and the other to vary the section of the light beampassing through the latter during the period of exposure.

The rate of variation of the section of the light beam traversing theobjective may be adjusted to have any one of the forms shown in Figs. 1to 6, i. e., it may decrease from the maximum aperture D determined bythe fixed diaphragm toward a minimum at the end of time T (Fig. 1), orincrease from a minimum to maximum aperture In Belgium May 6;

D in time interval T (Fig. 2), or first increase and then decrease (Fig.3) or decrease and then increase iFig. 4), or again exhibit variouscombinations of those described as shown in Figs. 5 and 6. 5

Whatever be the rate of variation of the section of the light beamtraversing the objective and falling upon the sensitive emulsion, eitherone of the assemblies shown in Figs. 8 and 9 may be used to produce theeffect desired.

In the form of structure represented in Fig. 8, and objective 0 isfitted with a fixed" diaphragm of the usual form (not shown) and ismounted so that an arcuate slot 3 in a rotatable shutter 9 movesthereacross so as to diminish the section 15 of the light beam passingtherethrough from a maximum value D to any minimum desired in a timeinterval T. The axis of slot 3 should be positioned to movesymmetrically with relation to the optic axis of the objective and willproduce 20 variations in the section of the light beam represented bythe diagrams in Figs. 7 and 8. In the diagram shown in Fig. 7, thenumerals I, 2, and 3 show how the variations in section would bedistributed for successive images in a cinemato- 25 graphic apparatuswhere T represents the exposure period and T the nonexposure intervalbetween successive photographs. For the diagram shown in Fig. 8, T and Thave the same significanoe, while t represents the angle through which30 the shutter turns during one half of its course and before theforward edge of slot 3 moves into alignment with the objective.

In the form of structure shown in Fig. 9, the shutter is provided with aslot of constant width 35 and variations in the section of the lightbeam traversing the objective are obtained by rapidly varying theopening of a diaphragm in timed relation to the movement of the shutter,the maximum amount of light capable of traversing the objective beinglimited by a second fixed diaphragm (not shown). Here shutter 9 isprovided with a slot 3 of constant width positioned to move across theoptic axis of objective 0, the effective section of the light beam trav-45 ersing the latter being varied by a diaphragm 2 whose aperture ischanged in timed relation to the rotation of disc 9 by the action of acam I reacting on a lever and link system 5, I to displace a finger 6acting directly on the diaphragm. 50 The relative timing of the shutterand diaphragm may be varied by shifting the position of pivotedextremity 8 of element 5 in a. manner which will at once be obvious tothose skilled in the art. The extreme positions of the lever and linksystem are represented by 5, 6, l and 5 6 and I In this form ofstructure, disc 9 may be completely eliminated if the variations in theaperture of diaphragm 2 are made sufilciently great to provide for aperiod of complete closure during displacement of the film the diameterof said aperture being varied only during the period of exposure.

In the form of apparatus shown in Fig. 8, which may serve either as aphotographing or projecting unit, slot 3 may be given any one of theforms shown in Figs. 10 to 12. If slots of the type of H, i l shown inFig. 10 be used, variations in aperture will take the form shown inFigs. 1 and 7. If, contrariwise, the slots be given the form andorientation shown in Fig. 11, the variation of aperture will follow thediagram shown in Fig. 2 when disc 9 turns in the directions of thearrow. Finally, if the slots be given some such form as is shown in Fig.12, any one of the forms of variation in aperture shown in Figs. 3 to 6may be produced.

In the case of the structure shown in Fig. 9, the form of variation ofthe aperture curve may be varied by changing the shape of cam 4 or theposition of pivot 8 along a graduated scale.

While the hereinabove described structures may be used for eitherphotographing cinematographically (or otherwise) or for projecting, itis found that the best eiTects are obtained by combining inverse efiectsduring the taking of the photograph and its subsequent projection. Forexample, a film may be exposed with the form of shutter shown in Fig. 10and projected with one of the form represented in Fig. 11, theintegration of effects thus obtained (corresponding to a summary of thevariations in Figs. 1 and 2) yielding a total effect corresponding tothat of a shutter of constant width or aperture (the summary of Figs. 1and 2 yields a substantially rectangular diagram).

In setting up the apparatus, the distance between the objective and thefilm or plate is adjustedsoastoobtainasharpimage intheioreground, thevarious planes toward the background coming automatically into focus asthe aperture varies. Contrariwise, it desired, the distance between theobjective and the emulsion may be set for the background, variations inthe aperture being designed to bring the foreground gradually intofocus.

The invention is, obviously, not limited to rotatable shutters but maybe applied to focal plane, oscillating and other types.

What I claim is:-

1. The method of producing monocular images in relief comprising thesteps of providing an objective and a light sensitive material, varyingthe efiective aperture of said objective during the period that light ispassing therethrough onto the light sensitive material, and projecting abeam of light through the image so obtained while varying the effectiveaperture of the projecting light beam during projection.

2. The method of producing monocular images in relief comprising thesteps of providing an objective and a light sensitive material varyingthe effective aperture of said objective during the period that light ispassing therethrough onto a light sensitive material, and projecting abeam of light through the image so obtained while varying the effectiveaperture of the projecting light beam during projection at an inverserate to that employed during exposure of the light sensitive material.

3. An apparatus of the class described comprising an objective, and amovable shutter, said shutter having a pair of coaxial slots formedtherein positioned to move across said objective, one of said slotspresenting portions oi. increasing section when said shutter isdisplaced in a predetermined direction, the other slot presentingportions of diminishing section when said shutter is displaced in thesame direction.

EMILE PIERRE LOUIS LE BARBIER.

